clippy: Fix warnings in components/shared (#31627)

* clippy: fix warnings in `components/shared`

* fix: formatting derive

* fix: rename new to default

components/shared/script_layout/lib.rs

@@ -49,11 +49,11 @@ pub struct StyleData {
     pub parallel: DomParallelInfo,
 }
 
-impl StyleData {
-    pub fn new() -> Self {
+impl Default for StyleData {
+    fn default() -> Self {
         Self {
             element_data: AtomicRefCell::new(ElementData::default()),
-            parallel: DomParallelInfo::new(),
+            parallel: DomParallelInfo::default(),
         }
     }
 }
@@ -86,20 +86,12 @@ impl StyleAndOpaqueLayoutData {
 }
 
 /// Information that we need stored in each DOM node.
-#[derive(MallocSizeOf)]
+#[derive(Default, MallocSizeOf)]
 pub struct DomParallelInfo {
     /// The number of children remaining to process during bottom-up traversal.
     pub children_to_process: AtomicIsize,
 }
 
-impl DomParallelInfo {
-    pub fn new() -> DomParallelInfo {
-        DomParallelInfo {
-            children_to_process: AtomicIsize::new(0),
-        }
-    }
-}
-
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum LayoutNodeType {
     Element(LayoutElementType),

components/shared/script_layout/message.rs

@@ -199,11 +199,11 @@ pub struct PendingRestyle {
     pub damage: RestyleDamage,
 }
 
-impl PendingRestyle {
+impl Default for PendingRestyle {
     /// Creates a new empty pending restyle.
     #[inline]
-    pub fn new() -> Self {
-        PendingRestyle {
+    fn default() -> Self {
+        Self {
             snapshot: None,
             hint: RestyleHint::empty(),
             damage: RestyleDamage::empty(),

components/shared/script_layout/wrapper_traits.rs

@@ -50,17 +50,11 @@ impl PseudoElementType {
     }
 
     pub fn is_before(&self) -> bool {
-        match *self {
-            PseudoElementType::Before => true,
-            _ => false,
-        }
+        matches!(*self, PseudoElementType::Before)
     }
 
     pub fn is_replaced_content(&self) -> bool {
-        match *self {
-            PseudoElementType::Before | PseudoElementType::After => true,
-            _ => false,
-        }
+        matches!(*self, PseudoElementType::Before | PseudoElementType::After)
     }
 
     pub fn style_pseudo_element(&self) -> PseudoElement {
@@ -138,9 +132,8 @@ where
     ConcreteNode: LayoutNode<'dom>,
 {
     fn new(root: ConcreteNode) -> TreeIterator<ConcreteNode> {
-        let mut stack = vec![];
-        stack.push(root);
-        TreeIterator { stack: stack }
+        let stack = vec![root];
+        TreeIterator { stack }
     }
 
     pub fn next_skipping_children(&mut self) -> Option<ConcreteNode> {
@@ -155,7 +148,9 @@ where
     type Item = ConcreteNode;
     fn next(&mut self) -> Option<ConcreteNode> {
         let ret = self.stack.pop();
-        ret.map(|node| self.stack.extend(node.rev_children()));
+        if let Some(node) = ret {
+            self.stack.extend(node.rev_children())
+        }
         ret
     }
 }